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286                                          FLORA JNDICA.
aware, been worked out in a comprehensive manner,—that is, with reference to the
germination of all Natural Orders. Lindley, on the other handj cites the fact of the
bases of the cotyledons elongating and emerging in germination, as "perhaps one of
the strongest arguments in favour of the lobes of the embryo being really cotyle-
3. Mizome. The true anatomy and structure of this organ is one,of the most diffi-
cult possible to demonstrate, nor do we profess to understand4 it thoroughly. "We
Bave attempted to trace the courses of the vascular bundles in .2V. pygmcsa, Lotus,
and stellata, both before reading TrecuTs paper and since, but without being able
to giye the necessary time, of which some idea may be formed from Trecnl's having
devoted more than a year to the study of NupAar Intea alone, the result of which, so
far as the rhizome was concerned, brought him no farther towards a definite con-
clusion than that " the structure of the stem, and of some other parts of the plant,
is what prevails in the greater number of plants that have one cotyledon.*' More
' recently, however, after the stndy of Victoria^ he expr&ses himself more positively,
and is " confirmed in his opinion of the analogy of structure that exists between
NympJueacea and Monocotyledons,"
Commencing with our own analysis, we found that the rhizomes presented a ccn- -
tral medullary mass, surrounded by a tolerably xvell-defmed zone of vascular bundles.
They differ from Exogcas in wanting liber, wood-wedges, and medullary rays, and in
the confused arrangements of the vascular tissue; and from Eiidogens in the vascular
zone surrounding a column of pith, in the arrangement of the vascular fascicles, and
in their composition. Our conclusion was, that tliis structure was quite reducible
to a very low aud deranged type of Exogenous stem, such as might be expected to
occur in a« axis of which all Hie intemodcs are crowded into the smallest possible
compass, and in a plant the habit and general arrangement of whose organs of support
and nutrition differ so widely from that of ordinary Exogens. In this opinion wo
were strengthened by some peculiarities in the structure of the abbreviated rhizomes
of other Exogcns, by the fact thai vascular bundles often do form a confused plexus*
at the nodes, and that their arrangement in these is hence not reducible to the Exo-
genous type which prevails in other parts of the same stem. The great deviations
From the normqi type in Menispermacea, and very many other plants of less peculiar
habit than N^ff^hcfacea, further confirmed us in this opinion, no less thau the fact
that there are mi Endogenous rhizomes known to ns with which those of tfywph&~
tteea can at all be compared. We may also repeat here what we have alluded to
under Menjwpermacea, that in our opinion a mere reduction of the Exogenous stem,
by the successive obliteration of its medullary rays and liber, and the confused arrange-
meut of its vascular bundles, by no means implies a transition to the Endogenous class.
We consider that there are other and far more important anatomical differences be-
tween these two great classes, and'that, to establish an Endogenous affinity for the
rhizomes orfsuck very anomalous plants as Nymphaacea> it is necessary to prove-the
existence of some, at any rate, of tho absolute characters of Endogeus, as the courses
of the vascular bundles and their composition.
Turning toJTrecul'&rheautiful analysis of the rWzorne of NupJutr tulp,a,. we do iioi
find pur opinion altered; these show the courses of the vascular bundles, and their
relations to the petioles, peduncles, and axis, with a precision that we, JaHe4 'to attain,
and we have full confidence in. their accuracy \ rTut there is nothing hi these that appears
to ns to establish an Endogenous affinity, and much that is seen in other Exogcns.
Henfrey's careful observations on the rhizome of Victoria differ from Trecul'a on
Nuphar, and he treats the subject rather differently. The rhizome of Victoria pre-
sents an almost solid axis of vascular bundles, not a zone of them. Its points of
affinity wfth Enflogcns Henfrey states to Be:—1. The apparently continuous develop-
ment of- a terminal bud. To this we would object that the real nature of the growing
point is not ItEely to be easily demonstrable in au abbreviated axis of so many inter*
nodes, and that other manifestly Exogenous rhizomes present % similar appearance.
2. That the roots are all adventitious This is perhaps the strongest point of any, but
its value in relation to the laws of germination in general cannot be said to be esta-